This invention relates to improved piston shaft seals for end-of-car hydraulic cushioning devices.
End-of-car hydraulic cushioning devices which are used to control forces transmitted to a railcar during high velocity impacts are well known in the prior art. Typical examples of such prior art cushioning devices and their components are illustrated in U.S. Pat. Nos. 2,944,639; 2,944,681; 3,047,162; 3,152,699; 3,207,324; 3,233,747; 3,301,410; 3,451,561; 3,463,328; 3,495,719; 3,568,855; 3,589,527; 3,589,528; 3,598,249; 3,604,568; 3,647,088; 3,752,329; 3,791,534; and 3,854,596.
With the continued improvements in prior end-of-car cushioning devices, particularly in the piston shaft and piston shaft seal assembly area, it has become desirable to improve the piston shaft seals of the cushioning devices to help eliminate oil leakage from the unit during a wide range of environmental operating conditions.